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Marc Mine - 2006 Annual Hydrology Report <br />4.0 MINE AREA ALLUVIAL GROUNDWATER <br />March 2006 <br />Field measurements of water quality parameters were taken at alluvial well AO-2A in October <br />2005 and on a monthly basis in 2006 from March through September. Field data are presented in <br />Appendix A, 2006 Field Data. Water samples were collected and analyzed in October 2005 and <br />in April and July of 2006. As of January 1999, the parameter list for alluvial well sample analysis <br />was reduced to include only major elements and no trace metals. The individual analyses of <br />samples collected are presented in Appendix C. Table 1, 2006 Groundwater Quality Statistics, <br />includes a summary of the water quality data for well AO-2A for the 2006 water year including the <br />minimum, maximum and mean values. The mean annual values for field parameters and the <br />laboratory results for the last 10 monitoring years are presented in Table 7, Site AO-2A Historic <br />Mine Area Alluvial Water Quality Data. The water levels recorded for AO-2A over the last 10 <br />years are shown on Figure 1, Mine Area Water Levels. Figure 2, EC vs. TDS-Well AO-2A and <br />2A, shows the relationship between electrical conductance (EC) and total dissolved solids (TDS) <br />levels since 1996. Note that the inaccurate EC readings were not inGuded on the figures. <br />Wells AO-2 and AO-2A are located in Bush Draw, downstream (east) of the northern extent of the <br />reclaimed Pit 1 area. In 1992, low water levels and the silted condition of well AO-2 resulted in <br />the inability to collect samples from this location. Well AO-2A was installed to a depth of 14 feet <br />in January 1993 and was located adjacent to well AO-2, replacing the original monitoring well. <br />See Map 1, Mine Anna Monitoring Stations, for the general well location. The change in wells is <br />apparent on the EC and TDS data. Well AO-2A has less dissolved constituents than the original <br />well. There was no obvious change in water quality in the 2006 water year. The calcium and <br />sulfate concentrations the last few years are notably less than well AO-ZA. Note that the field <br />equipment utilized for measuring EC malfunctioned and was replaced in 2006. <br />TABLE 7 -SITE AO-2A HISTORIC MINE AREA ALLWIAL WATER QUALITY DATA <br /> AO-2 AO-2A <br />Anal 1997 1998 1999 2000 2001 2002 2003 2004 2005 2008 <br />Tern °C 9.3 7.4 9.3 10.7 10.0 9.8 10.7 10.0 11.3 13.4 <br />H su 7.5 7.6 7.6 7.6 7.4 7.6 7.7 7.6 7.7 7.8 <br />EC hoslcm 20°C 638 871 1200 1300 1167 1063 633.3 333.3 (`) 200 (') 648 <br />TDS 580 817 1060 1233 1037 977 620.0 680.0 600 470 <br />SAR in water 1.97 2.84 2.39 2.78 2.50 2.44 2.60 2.60 3.02 2.16 <br />Calcium dissolved 70.2 91.9 127.3 137.0 116 108.2 64.7 74.5 59.7 SZ.t <br />Sodium dissolved 80 131 130 158 127 123 101.3 105.9 111.1 75.3 <br />Ma nesium dissolved 34.7 46.0 60.6 69.2 56.6 55.9 32.1 35.7 28.7 24.7 <br />Potassium dissolved 4.4 3.9 4.0 3.9 3.4 3.7 2.7 2.7 2.2 2.3 <br />Sulfate 153 280 490 617 527 453 237 257 173.3 181.7 <br />Chloride 5.5 11.7 16 18 14 13 9 11 3.7 5.3 <br />Carbonate as CaC03 <2 <2 5.3 <2 <2 <2 c2 <2 <2 <2 <br />Bicarbonate as CaC03 302 373 317 319 272 279 262 283 378.3 261.7 <br />Fluoride 0.4 0.4 0.4 <br />Nitrate-Nitro en diss 0.53 0.26 0.14 0.18 0.10 0.09 0.06 0.04 0.58 0.12 <br />Iron dissolved 0.22 0.12 0.10 0.07 0.20 0.24 0.33 027 0.17 0.30 <br />Man anese dissolved 0.35 0.80 0.81 0.67 0.80 1.09 0.55 0.57 0.295 0.281 <br />Note: All values represent water year mean concentrations in mgA unless otherwise noted. <br />= Equipment malfunction <br />File: 6371/2006/20(16 hydrolo®cpt Page 9 <br />